Synthesis of Iron Telluride and Graphene based Nanomaterialsfor Sensing and Photocatalytic Applications
| Autor: | Prathik Roy, 羅伊 |
|---|---|
| Rok vydání: | 2013 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 101 This thesis focuses on synthesizing nanomaterials for sensing of glucose and mercury in blood, and photocatalysis of highly toxic pollutants such as nitrobenzene. My thesis is divided into four parts. Chapter one introduces the background of nanomaterials as sensors, the concept of enzyme mimics for colorimetric bio-sensing purposes, as well as an introduction to semiconductor photocatalysts, unique properties offered by photocatalytic nanomaterials for nvironmental remediation. In chapter two, iron telluride nanorods (FeTe NRs) were prepared from Te nanowires through a galvanic reaction, that act as enzyme mimics and possesses strong catalytic activity towards the oxidation of a peroxidase substrate (ABTS) by H2O2, enabling the detection of H2O2 and glucose with a limit of detection (LOD) of 55 nM (linear range = 0.1_5 μM) and 0.38 μM (linear range = 1_100 μM) respectively, which is better than other iron based nanomaterials and horse radish peroxidase (HRP). It is also found that the release of Fe2+ ions plays a critical role in the high catalytic activity. The third chapter utilizes the FeTe NRs based system for the detection of mercury with a limit of detection of 1.31 nM at a signal-to noise ratio of 3 and a linear range of 5 to 100 nM (R2 = 0.99), through a cation exchange reaction between FeTe NRs and Hg2+ as a colorimetric biosensor for total mercury in blood. The sensing system exhibits excellent sensitivity for mercury. The final chapter deals with the development of graphene-ZnO-Au nanocomposite (G-ZnO-Au NC) through a simple hydrothermal approach, which acts as a highly efficient photocatalyst under UV light for the reduction of nitrobenzene to aniline under 140 min with an yield of ca. 98 %. The photocatalytic activities of the nanocomposite are 3.5 and 4.5 fold higher than that of commercial TiO2 and ZnO nanospheres (NSs) respectively, it also exhibits excellent durability with a decrease of only 7% in the conversion efficiency after 5 cycles. A detailed study on the mechanistic path of the VIII photocatalytic reduction reveals that reduction of nitrobenzene to aniline is most efficient in the absence of oxygen, as oxygen tends to compete for the photo-generated electrons. G-ZnO-Au NC photocatalyst has the potential to find real world applications in the near future for environmental remediation. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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